It is well known to provide a sieve or sieves in the grain cleaning system of an agricultural combine. Typically, the cleaning system will consist of two sieves, an upper or coarser sieve or chaffer located below the threshing mechanism or separator of the combine and having larger sieve openings for the passage of grain and smaller elements of plant material therethrough but relatively little of the larger chaff, and a lower finer sieve located below the chaffer for receiving the grain and smaller elements of plant material therefrom and having smaller sieve openings for passage of the grain therethrough but relatively little of the plant material. The collected and cleaned grain, once through the sieves is then typically transported by conveyor or other means to a clean grain tank or bin on the combine, or to an accompanying grain receiving vehicle.
A typical sieve construction includes a plurality of elongate parallel, pivotally mounted slats, each slat including a plurality of longitudinally spaced upwardly extending inclined fingers, the slats being pivotable through a range of open positions angularly oriented to horizontal for providing a corresponding range of openings or spaces between the fingers of adjacent ones of the slats. A sieve may be adjusted to a desired opening at the commencement of the harvesting operation, and may be reset at times during the harvesting operation, either mechanically or automatically, to achieve a desired crop yield rate. It may also be necessary to access the sieve, during or after the harvesting operation, to clear any chaff, plant material, debris, or the like that may become lodged in the spaces or openings in the sieve.
It may also be necessary to remove the sieve for cleaning, service, replacement, and the like. Generally the sieves are mounted and retained in the combine using hardware, such as nuts and bolts accessed from the side of the combine. Accordingly, this mounting arrangement requires opening a side panel on the combine, locating the retaining hardware on the inside of the sieve support structure, which may or may not be visible or readily accessible from the outside of the combine, and removing the retaining hardware. Then the procedure is repeated on the opposite side of the combine. Once the retaining hardware is removed from both sides of the combine, the sieve may be removed from the rear of the combine by lifting the sieve from its support structure and then pulling it from the rear of the combine. The procedure must be reversed to mount and retain the sieve when replaced. Since the retaining hardware (nuts and bolts) is removed from the support structure prior to removing the sieve, these small pieces of hardware can easily be dropped and/or lost during subsequent cleaning or service of the sieve resulting in delay and additional down time for the combine. Also, in some instances, the upper sieve, or chaffer, must be removed whether or not it needs maintenance, just to gain access to the lower sieve. Finally, removal and/or replacement of the sieve by lifting and/or lowering the sieve relative to its support structure can be difficult and undesirable.
As a result, what is sought is a sieve retainer which is more accessible, preferably solely from the rear of the combine, and which provides improved and easier access to, and removal and replacement of the sieve without significant lifting.